The present invention relates generally to vehicle supplemental inflatable restraint systems and, more particularly, to an air bag module that provides variable output inflation of an air bag cushion from a single inflator.
Driver side or passenger side supplemental inflatable restraint (SIR) systems typically include an air bag stored in a housing module within the interior of the vehicle in close proximity to either the driver or one or more passengers. SIR systems are designed to actuate upon sudden deceleration to rapidly deploy an air bag to restrain the movement of the driver or passengers. During deployment, gas is emitted rapidly from an inflator into the air bag to expand it to a fully inflated state.
Air bag passive restraint systems include an inflator, which produces gas to inflate the air bag cushion. Known inflators for air bag cushions are generally of three types. One type is the pure gas inflator wherein a pressure vessel contains stored pressurized gas. The pressure vessel communicates with the cushion through various types of rupturable outlets or diaphragms. Another type is the gas generator wherein a propellant is ignited and the resultant gases flow through an outlet to the cushion. A third type is the hybrid or augmented type. This type includes a pressure vessel containing stored pressurized gas and a gas generator. When the generator is ignited, the resultant gas flows with the stored gas to the cushion through the pressure vessel outlet.
It is also known to inflate the cushion at a relatively low rate under low level deployment conditions, such as a sudden low level deceleration, and at a relatively high rate under high level deployment conditions, such as a sudden high level deceleration. This can be accomplished in a pure gas type inflator by providing the pressure vessel with an outlet of variable flow area. In addition, devices are known which provide primary inflation (reduced inflation) and full level inflation using a single gas vessel with two separate gas heaters. Primary inflation is accomplished by actuating the gas vessel and heating the gas at a specified reduced level. Full level inflation is accomplished by actuating a second separate heater located at the bottom of the gas vessel to heat the gas at a greater level. This second heater is deployed at the same time or a delayed time as the primary heater to provide full level inflation.
It is also known in the art to use a system having two discrete inflators to accomplish dual level inflation. In these types of systems, two discrete inflators are deployed at the same time or at a delayed time depending upon the severity of the sudden deceleration.
This invention offers advantages and alternatives over the prior art by providing an air bag module having a slide for selectively restricting the gas flow passing from an inflation chamber to an air bag cushion to provide different levels of air bag deployment. Advantageously, the housing of the air bag module includes openings to permit gas flow to the air bag cushion and venting apertures for providing a path directing gas flow away from the air bag cushion to reduce the level of deployment. The slide may selectively restrict the gas flowing into the air bag chamber through the openings of the housing, or selectively restrict the gas exiting the chamber through the venting apertures of the housing to provide a simple means of varying the level of deployment of the air bag cushion. Furthermore, another embodiment including a flap disposed in the housing provides an economic means of providing dual inflation of the air bag cushion by selectively diverting gas from the air bag cushion under reduced level deployment conditions.
These and other advantages are accomplished in a preferred form of the invention by providing an air bag module that provides dual inflation levels of an air bag cushion in response to rapid deceleration of a vehicle. The air bag module has a housing that defines a chamber. A vent aperture disposed in the housing provides fluid communication between the chamber and exterior of the housing. The air bag cushion is secured to the housing in fluid communication with the chamber through first openings disposed in the housing. An inflator releases gas to inflate the air bag cushion in response to one of a first and second deployment conditions. An actuator moves a slide from a first position to a second position in response to the first deployment condition. The first position permits a first predetermined level of fluid communication between said chamber and air bag cushion and the second position permits a second predetermined level of fluid communication between the chamber and air bag cushion. The first predetermined level of fluid communication is different than the second predetermined level.
In accordance with another embodiment of the invention, an air bag module has a housing that defines a chamber. The air bag cushion is secured to the housing in fluid communication with the chamber through first openings disposed in the housing. An inflator releases gas to inflate the air bag cushion in response to one of a first and second deployment conditions. A vent aperture disposed in the housing provides selective fluid communication between the chamber and exterior of the housing. The vent aperture provides a first level of fluid communication under the first level deployment condition, and a second level of fluid communication under the second level deployment condition.
In accordance with other preferred aspects of the other embodiment of the invention, the air bag module further includes an actuator that moves a slide from a first position to a second position in response to the first level deployment condition. The first position permits a first predetermined level of fluid communication between the chamber and exterior of the housing, and the second position permits a second predetermined level of fluid communication between the chamber and the exterior of the housing. The first predetermined level of fluid communication is different than the second level of fluid communication.
In addition, the venting aperture maybe a deformable flap disposed in the housing of the air bag module. An actuator includes a stop disposed adjacent the flap that moves between an extended position to prevent the opening of the flap under full level deployment condition and a retracted position to permit the opening of the flap during reduced level deployment condition.